1. Field of the Invention
This invention relates generally to solid state scanning devices and more particularly to a system of detecting and analyzing the color of light falling on a solid state imaging device or scanner.
2. Description of the Prior Art
Solid state imaging arrays are well known to the art. U.S. Pat. No. 3,721,839 describes a typical solid state imaging array. The array, described in this patent, employes junction FET's as the photoelements. Each of these JFET's is biased so that under illumination it is conductive. The use of such JFET's achieve a higher signal to noise ratio than prior art vidicons.
The present invention, however, describes an improved solid state imaging array for operation in the charge storage mode which provides not only the high signal to noise ratios achievable by the prior art but also has a density structure, increased speed of response, and significantly increased resolution not achievable by the prior art.
A further object of the invention is to provide a high density semiconductor imaging array easily fabricated with present techniques.
Still another object of the invention is to described a complete integral solid state system for detecting and analyzing the color of light impinging on the imaging array of the invention.
Still another object of the invention is to describe a large area scanning system by utilizing an array of photoelements coupled to a series of shift registers sensing the current created in the photoelements by the different colors of light impinging on the photoelements and again analyzing the current output of the photoelements to determine the colors of the lights falling on the photoelements.
These and other objects of the present invention are achieved by employing a complete solid state scanning system integrated in a single crystal wafer of one type conductivity semiconductor material. The wafer is provided with a relatively thin layer of the opposite type conductivity diffused or ion-implanted therein and a plurality of insulated electrodes on its surface that, when biased, will provide a depleted region between the surface and the junction between the two conductivity regions. When light enters the body of the wafer it is absorbed by the semiconductor material of the substrate at the depth of penetration of the light and a photocurrent is generated. Because the depth of penetration of the light is a function of the color of the light impinging on the element, analysis of the depth of the generated photocurrent can determine the color of the light impinging on the array.